Solid Waste & Recycling


Closing the Phosphorous Loop

Amongst all the challenges to environmental sustainability, there is one that few people today have even heard of, but which within a generation could likely become the most pressing concern for humanity globally. The issue has already prompted...

Amongst all the challenges to environmental sustainability, there is one that few people today have even heard of, but which within a generation could likely become the most pressing concern for humanity globally. The issue has already prompted various national governments to take action, and is now just beginning to receive attention in mainstream scientific media.

A Canadian company based in Vancouver, BC has already found the solution, and it originates from almost every household in the country.

When most Canadians flush the toilet they don’t give much thought to what happens next. In most cases the sewage flows to a municipal treatment plant to be cleaned before the water is discharged back into the environment. The cleaning process needs to remove various contaminants from the sewage to prevent them from polluting our waterways, and as our society has developed, the quality of this treatment has improved, driven by federal and provincial regulation. Much of the focus for this improvement now focuses on nutrients — nitrogen and phosphorus — which an increasing number of wastewater treatment plants facing more stringent regulations on nutrient disposal must deal with.

Phosphorus originates from phosphate rock, which is mined from a relatively limited number of deposits and converted into fertilizer for applications such as growing agricultural crops. The element is required by every form of life on earth, including humans, and the food we eat. The vast majority of the phosphorus we consume ends up in our waste, however; hence the need for wastewater treatment plants to remove it.

Until recently, removing it was the end of the story, but now a Canadian company — Ostara Nutrient Recovery Technologies Inc. — has developed a process that enables the phosphorus to be recycled back into a high-purity fertilizer product.

Estimates of global phosphate rock reserves vary, but some put it at as little as forty years. Further, being an element, it cannot be substituted (unlike, say, the renewable energy used to replace our dependence on fossil fuels). That’s why closing the loop by recycling this material is so important.

Ostara’s technology, branded the PEARL™ Process, was developed at the University of British Columbia, and was then commercialized in May 2005 when the company was founded. Headquartered in downtown Vancouver, BC, Ostara is backed by VantagePoint, a venture capital firm that has appointed Robert F. Kennedy to Ostara’s board.

Since 2005, Ostara has successfully scaled up the technology from the lab to a commercial level and constructed two full scale facilities, the first of their kind in the world.

The first of these (in Edmonton, Alberta) became operational in May 2007, and the second (in Portland, Oregon) in May 2009. Another two facilities are currently under construction in the Suffolk, VA and York, PA.

The technology

The technology is based on the precipitation of phosphorus, together with magnesium and nitrogen (in the form of ammonia), in a fluidized bed reactor. The material that’s precipitated is a mineral deposit called Struvite (MgNH4PO4.6H2O), and the “magic” of the PEARL Process is the way the Struvite is formed into small, hard pellets, which are ready for use as a fertilizer without any further processing.

Struvite deposits often form accidentally in wastewater treatment plants, where they occur as a concrete like scale, causing pipes to block and equipment such as pumps and valves to fail. By forming Struvite under controlled conditions, Ostara’s process prevents this accidental scaling, saving treatment plant owners significant operating costs.

Further, by removing phosphorus and nitrogen and converting these nutrients into fertilizer, the job of the treatment plant in ensuring these potential contaminants are not discharged into the environment is made easier, which again saves money, and also helps to secure regulatory compliance.

The conventional treatment alternative to the PEARL Process is the dosing of chemicals which bind to the phosphorus; not only is this costly — it prevents the valuable element from being recovered.

In contrast, Ostara’s process produces a premium fertilizer branded Crystal Green®. The company takes responsibility for marketing this fertilizer and commits to share the sales revenue generated back with the treatment plant owner. All of these financial benefits result in very attractive payback periods, typically from three to five years.

In summary, Ostara’s technology:

• Promotes environmental sustainability by recovering polluting nutrients, such as phosphorus and nitrogen, from sewage sludge liquids that would otherwise be released into the environment;

• Helps wastewater treatment plants reduce chemical demand and other operating costs and increase throughput capacity;

• Converts the recovered nutrients into a high value slow-release fertilizer product that is being sold in the turf and nursery industries;

• Displaces greenhouse gas-intensive phosphate fertilizer production methods.

Phillip Abrary is President and CEO of Ostara Nutrient Recovery Technologies Inc. in Vancouver, BC. Contact Phillip at

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